ejthomp

2005 LS430 95,000 miles

Air conditioner stopped working. My wife drives this car and since it just recently has gotten hot enough for my wife to notice the lack of A/C, I'm not sure how long it has been out. Fans and switches inside the car seem to work normal, just the air isn't being cooled at all.

I can't hear the A/C compressor cycle on when the A/C is turned on. The cooling fans don't turn on either.

I checked for A/C codes and I'm not getting any unusual.

If the compressor isn't even cycling on and the fans aren't coming on either, doesn't this point more toward the high pressure switch than the compressor?

I'm tempted to buy a new switch and go down to my local auto repairman and ask him to change the switch and reacharge the system. What would I be out? $100 if it didn't work?

If it is the A/C compressor, I'll probably just do that myself to save a few bucks and then just pay for the recharge.

Thoughts?

BradTank

I'd first see if it's low on refrigerant.

Even though it's a closed system, small amounts of refrigerant can leak out over long stretches of time. It's also more likely to happen in places where the AC isn't used as much. So before I had someone replace parts, that's where I would start.

You can get an inexpensive gauge and check it yourself as well.

yoitskenn

iTrader: (4)

I agree. Check the refrigerant. If it's low or empty the AC compressor won't kick on.

StanVanDam

The purpose of the sight glass in front of the radiator is to do a basic check of refrigerant volume. Turn on your engine, set front and rear AC on max cold and max fan speed, fully open all the doors, and hold the engine at 1500rpm.

If you see bubbles in the sight glass, that means you are low on refrigerant - check for leaks (especially if you have dual-AC, the line going to the rear is prone to corrosion - see https://www.clublexus.com/forums/ls-...sure-line.html), repair all leaks, then add refrigerant until bubbles disappear.

If no bubbles exist and your AC blows warm/ambient, you are empty.
If no bubbles exist and there is a considerable temperature difference between inlet and outlet, then you have proper or excessive refrigerant.

If immediately after AC is turned off, refrigerant foams and then becomes clear, you have the proper amount of refrigerant.

For more precise measurements, use a manifold gauge set. Set your AC on RECIRC, run engine at 2000rpm, blowers on max speed, temp at max cold. Low pressure side should read 0.15-0.25 MPa, high pressure side should read 1.37-1.57 MPa.

The amount of refrigerant after a vacuum purge for single AC is 650 +/- 50g, 900 +/- 50g for dual-AC.

If you replace the compressor, you need to remove oil from the new compressor using this formula:

(Oil capacity inside the new compressor: 130 +15 cc (4.4 +0.5 fl.oz) ) − (Remaining oil amount in the removed compressor) = (Oil amount to be removed from the new compressor when replacing)

Because compressor oil remains in the pipes of the vehicle, if a new compressor and magnetic clutch is installed without removing some oil inside, the oil amount becomes too much, preventing heat exchange in the refrigerant cycle and causing refrigerant failure.

rkw77080

Assume you have checked the relevant fuses already?
Passenger-side Fuse Box: 7.5A "P-IG" and 7.5A "P-ACC"
Driver-side Fuse Box: 7.5A "A/C"
Engine Bay Fuse Box: 7.5A "A/C IG"

ejthomp

Thank you guys so much!!!!!

I was able to temporarily kick it on by revving the motor. Then I see air bubbles running through the sight glass. Obviously low on refrigerant. Now the question is "Why?"

This vehicle is very clean and does not have the rear air. Right now I'm thinking I will have some refrigerant added and see how long it lasts.

ejthomp

I added some refrigerant. The low-side pressure was just under 25 PSI. The A/C runs cold now at 45F. I'm going to check it for leaks tomorrow. I've had plenty of vehicles and this is the first time I've had to add refrigerant. This makes me think my fix is temporary.